1. Field of the Invention
The present invention relates to the field of motor powered mounting bases and pedestals for supporting and controllably raising and lowering work tables, equipment benches, and the like.
2. Description of the Related Art
There are numerous occasions on which it is desirable to precisely position a working surface (e.g. table top) or equipment mount to facilitate worker access or alignment of equipment to a related operation. A common example is the need to elevate a table or desk top an appropriate height before seated workers, each of which might have different optimum working levels. Such is the case of a keyboard operator using a computer or data terminal, and it is currently well known that operating such equipment for extended periods at improper height can lead to chronic maladies such as eyestrain, back distress, wrist/hand disorders, etc. These problems can often be relieved by the worker adjusting the height of the work surface to a level appropriate for his particular body proportions. Moreover, occasional change in level can also be beneficial to relieve fatigue and temporary discomfort.
Because a desk top is often laden with heavy computer equipment, books, etc. it is desirable that the vertical adjustment of such a system be smoothly powered by a motor rather than manually. Further a properly arranged electric or hydraulic drive can provide a smooth adjustment of height to virtually any desired precision.
With recent widespread accommodation of handicapped workers into factories and offices, such adjustable work platforms are even more desirable. Workers who are in wheelchairs for example cannot readily move from their wheelchair to another work stool or chair of optimum height, and therefore need to be able to adjust the work surface to the proper height for them to work from their own wheelchair. A precisely controllable powered lifting system is of particular advantage to many handicapped workers who have less than normal strength in their upper bodies.
Powered lifting bases for work surfaces have been provided in the past, but it is common for these to have single or dual supports centrally disposed under the work surface. Such designs, either hydraulically, screw, or gear driven minimize off-set loading, distortion, and binding of the lifting mechanism, but at the expense of blockage of the space under the work surface. Such arrangements are particularly objectionable for workers in wheelchairs, because of the somewhat larger clear space required to accommodate the wheelchair, legs, and feet of the handicapped worker, and the limited ability of such a worker to easily adjust to interference of the blocking pedestals, legs, and cross members of such devices.
Recently desktops have evolved to shapes other than the traditional rectangle. It is not uncommon to encounter L-shaped surfaces as computer work tables which are situated in the corner of an integrated office furniture system/cubicle. The elongated feet under the legs of such systems are normally parallel in a direction running perpendicular to the front edge of the work top, or they are arranged to run perpendicular to the back walls such that they toe-in towards the front of the work top. In either case, the front tips of the elongated feet are forced to be as close together as the foreshortened front edge of such a corner work top, and therefore they create an even narrower space within which to fit a wheelchair.
While these problems and objections could be overcome by moving the vertical supporting legs close to the rear of the work top and arranging the feet to align with the back corner walls at an angle opening toward the front edge of the top, designs based on the prior art do not have the geometry, rigidity, stability, or lack of binding sufficient to be so arranged. What is needed and what has not yet been provided by the prior art is a table lifting device having vertical supporting legs of sufficient stiffness to be positioned near the back of the work top, having internal bearings such that the vertical driving mechanism can operate smoothly without binding under the offset load on the work top which will necessarily be cantilevered toward the front of the top and thereby create substantial bending moments in the legs, and having feet spreading at an angle opening toward the front of the work top to provide maximum clear space under the work top to accommodate a wheelchair, workers legs and feet, etc.